The Concept of Emergence

An emergent property is one describing a
higher level of organization of matter, where the description is not
epistemologically reducible to lower-level concepts.

A classic example would be that of an
ecosystem. In order to understand organisms co-existing together we need this
concept, and cannot reduce it out of our understandings. (Come to that, the
concept multi-cellular organism is itself emergent - simply to describe an
animal as a collection of cells living together is to miss a great many
properties characteristic of the way those cells co-operate.)

Two notes of caution:

we are not here referring to temporal emergence - a more
complex system developing over time from a simpler, but to
emergence within our levels of
description.

the sort of reductionism on which we have just been
concentrating concerns epistemology, the state of our ability to describe
a subject. This is subject to change, and it is indeed conceivable that a
property regarded at one time as emergent might later be deduced from the
properties of a simpler system.

What actually happened in the history of
molecular biology was most interesting. A number of scientists, Crick included,
first began to consider questions of the chemistry of life because of a series
of lectures given by the physicist Erwin Schrödinger in Dublin in 1943, and
published as What is Life?The remarkable success of the
investigations of such figures as Linus Pauling, Max Perutz, Francis Crick and
James D Watson gave momentum to this programme of redescribing biology in terms
of physics and chemistry, but has not effected a reduction of the one to
the other. Rather all sorts of emergent
properties have been recognised at the interface between biology and chemistry.
Francis Cricks aim to reduce all biology to chemistry and physicshas not been realised.